 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
OPA561 Datasheet(PDF) 9 Page - Texas Instruments |
|
||||||||||||||||||||||||||||||
OPA561 Datasheet(HTML) 9 Page - Texas Instruments |
|
|
9 / 17 page  OPA561 SBOS206E − DECEMBER 2001 − REVISED FEBRUARY 2007 www.ti.com 9 OUTPUT PROTECTION Reactive and EMF-generation loads can return load current to the amplifier, causing the output voltage to exceed the power-supply voltage. This damaging condition can be avoided with clamp diodes from the output terminal to the power supplies, as shown in Figure 4. Schottky rectifier diodes with a 3A or greater continuous rating are recommended. OPA561 Flag I LIM E/S 47 µF Output Protection Diode Output Protection Diode V O R O 100k Ω +V −V 5 4 8 7 6 3 2 0.1 µF 0.1 µF 47 µF Figure 4. Output Protection Diode THERMAL PROTECTION The OPA561 has thermal sensing circuitry that helps protect the amplifier from exceeding temperature limits. Power dissipated in the OPA561 will cause the junction temperature to rise. Internal thermal shutdown circuitry shuts down the output when the die temperature reaches approximately 160 °C, resetting when the die has cooled to 140 °C. Depending on load and signal conditions, the thermal protection circuit may cycle on and off. This limits the dissipation of the amplifier, but may have an undesirable effect on the load. Any tendency to activate the thermal protection circuit indicates excessive power dissipation or an inadequate heatsink. For reliable, long-term, continuous operation, junction temperature should be limited to +125 °C, maximum. To estimate the margin of safety in a complete design (including heatsink), increase the ambient temperature until the thermal protection is triggered. Use worst-case loading and signal conditions. For good, long-term reliability, thermal protection should trigger more than 35 °C above the maximum expected ambient condition of your application. This produces a junction temperature of +125 °C at the maximum expected ambient condition. The internal protection circuitry of the OPA561 was designed to protect against overload conditions; it was not intended to replace proper heatsinking. Continuously running the OPA561 into thermal shutdown can degrade reliability. The E/S pin can be monitored to determine if shutdown has occurred. During normal operation the voltage on the E/S pin is typically above (V−) + 2V. During shutdown, the voltage drops to less than (V−) + 0.8V. POWER DISSIPATION Power dissipation depends on power supply, signal, and load conditions. For DC signals, power dissipation is equal to the product of output current times the voltage across the conducting output transistor. Dissipation with ac signals is lower. Application Bulletin AB−039 (SBOA022) explains how to calculate or measure power dissipation with unusual signals and loads, and can be dowloaded from www.ti.com. HEATSINK AREA The relationship between thermal resistance and power dissipation can be expressed as: where: TJ = Junction Temperature (°C) TA = Ambient Temperature (°C) qJA = Junction-to-Ambient Thermal Resistance (°C/W) PD = Power Dissipation (W) To appropriately determine required heatsink area, required power dissipation should be calculated and the relationship between power dissipation and thermal resistance should be considered to minimize shutdown conditions and allow for proper long-term operation (junction temperature of +125 °C). Once the heatsink area has been selected, worst-case load conditions should be tested to ensure proper thermal protection. For applications with limited board size, refer to Figure 5 for the approximate thermal resistance relative to heatsink area. Increasing heatsink area beyond 2in2 provides little improvement in thermal resistance. To achieve the 32 °C/W stated in the Electrical Characteristics, a copper plane size of 9in2 was used. The HTSSOP-20 PowerPAD package is well suited for continuous power levels from 2W to 4W, depending on ambient temperature and heatsink area. Higher power levels may be achieved in applications with a low on/off duty cycle, such as remote meter reading. Not Recommended for New Designs |
Similar Part No. - OPA561 |
|
Similar Description - OPA561 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
